I am actually not all that sure. To a greater or lesser extent, I think so, but how much of it was deliberate originally -- it was building up for a long time, but it came to a head the time Peter crashed test-flying planes and that was basically the incident that set Susan off. And she knows exactly where to hit her siblings where it hurts. (Peter got off lucky; he was so drugged up he didn't really know what was going on at the time.)